textproduct: Rapid City

KEY MESSAGES

- Warmer through today, then becoming unsettled and cooler.

- Strong to severe storms possible this afternoon across western SD.

- Elevated to near critical fire weather conditions today across portions of northeast WY.

- Wildfire smoke is expected to linger much of the week, with thicker smoke at times across the western third

UPDATE

Issued at 131 AM MDT Tue Aug 11 2026

Weak, isolated convection has popped up east of the Black Hills in the last hour or so. SPC mesoanalysis depicts 3000-4000 J/kg MUCAPE over much of western SD which will fuel isolated, elevated convection through the next few hours. Have added low PoPs over portions of the western SD plains to account for this. The supercell in central SD that caused quite a bit of severe weather this evening has weakened greatly and continues to move southeastward. Some areas in south central SD may see some hail and gusty winds but not anticipating any further severe weather overnight.

Attention turns towards later today/this afternoon. CAMs continue to show storms developing over northwestern SD into the Black Hills after 21-22z (3-4 pm MDT) as corridor of 2500-3500 J/kg MLCAPE develops over the area. Effective shear of 40-50KT and forecast wind profiles supportive of supercell structure with large to very large hail being the main hazards of concern (though damaging wind gusts are also possible).

DISCUSSION

(This Evening Through Monday) Issued at 1249 PM MDT Mon Aug 10 2026

Early this afternoon, we are still watching and waiting to see if we can get some storms going. Thunderstorm chances are still highly conditional and will depend on whether or not we can break the cap. Yesterday, one storm was able to develop and as of this writing, clouds are building over the central Black Hills. So it's possible.

For tonight, any storms that are able to develop, they will move east through the evening. Overnight looks quiet with diminishing winds and overnight lows in the 50s to 60s.

Tuesday looks similar to today, with highs mostly in the upper 80s to 90s. Zonal flow will keep the daily chances for afternoon storms in place. SPC has placed a Slight (level 2 of 5) over the central SD counties for Tuesday.

The SPC has also placed a Slight risk of severe weather on Wednesday over SW SD. Modest westerly winds aloft will be over the central High Plains Wednesday with a surface low developing near the CO/KS border. Easterly surface winds north of the low over Nebraska into southern South Dakota will maintain moisture and instability into the area. Storms will form over the High Plains and move eastward through the evening. Hail may occur initially, with damaging gusts possible during the evening.

Unsettled pattern under zonal flow will give the area cooler temps and daily chances for rain and storms for the second half of the week.

AVIATION

(For the 18Z TAFS Through 18Z Wednesday) Issued At 1148 AM MDT Tue Aug 11 2026

Low clouds have burned off, leaving clear and humid conditions in their wake. Still expecting TSRA to develop acros the Black Hills and parts of NW SD after 20Z this afternoon. Continued the PROB30 group for KRAP for the late afternoon. Local MVFR cigs/vsbys are possible with some of the stronger storms, along with hail and erratic winds.

FIRE WEATHER

Issued At 1249 PM MDT Mon Aug 10 2026

Critical fire weather conditions are developing across northeastern WY and far southwestern SD early this afternoon. Critical fire weather conditions will last into the evening. A Red Flag Warning is in effect for these areas.

Hot and dry weather with elevated fire weather conditions (especially over northeastern WY) will continue through the mid week. Cooler and unsettled weather moves into the region by Wednesday and continues through the late week.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.